(a) Field of the Invention
The present invention relates to sythetic crystalline titanium-boron-oxide, synthetic crystalline materials based thereon containing an oxide of aluminum or silicon or combinations thereof and to methods for their preparation. These materials are useful as catalysts for organic compound conversion and in their metal-loaded form as photocatalysts for the cleavage of water.
(b) Description of Prior Art
The synthesis of zeolites and zeolitic materials has been pursued for nearly 50 years, and the literature is filled with reports on structure, methods of preparation, and uses for these materials.
The synthesis of aluminosilicates, the microporous silica polymorphs, titanium aluminophosphates and borosilicate molecular sieves has received much attention in both open and patent literature.
Hydrothermal techniques are typical methods of synthesis used for more than 150 varieties of synthetic molecular sieve zeolites. The techniques consist of the preparation of a gel comprising a source of alkali and water. However, reports on the synthesis of zeolitic materials from organic solvent systems are few.
Bibby et al. reported the synthesis of silica-sodalite and aluminosilicate-sodalites from ethylene glycol and propanol, in Nature, Vol. 317 (1985) p. 157, and van Erp et al. synthesized BaT, hydroxysodalite and kaliophilite using organic solvents, such as glycol, glycerol, sulpholane, dimethyl sulfoxide, ethanol, etc., in Zeolites, Vol. 7 (1987) p. 286.
Recently, Oisheng et al. synthesized pentasil-type zeolites using ethylene glycol, glycerol and butyl alcohol in J. Chem. Soc., Chem. Commn., (1988) p. 1486. Also, various boron-containing inorganic oxides, identified as Bolite, have been synthesized by Asaoka in U.S. patent application Ser. No. 207,295, (1988). The non-aqueous route is especially suited for the preparation of these oxides using tetraalkyl orthotitanates and/or tetraalkyl orthosilicates and/or trialkyl aluminates and orthoboric acid.
A family of Bolites comprises seven types of oxide species, namely, Bolite-1 Ti-Al-Si-B-O, Bolite-2 Ti-Al-B-O, Bolite-3 Al-Si-B-O, Bolite-4 Ti-Si-B-O, Bolite-5 Ti-B-O, Bolite-6 Al-B-O and Bolite-7 Si-B-O.
Generally, zeolites and zeolitic materials include a wide variety of natural and synthetic crystalline materials. These are crystalline aluminosilicates, aluminoborosilicates and titanoborosilicates containing positive ions, such as alkali metal or alkaline earth metal ions. The Bolite materials include neither monovalent alkali metals nor divalent alkaline earth metals.
U.S. Pat. No. 4,519,998 which is here considered relevant discloses the crystalline titanoborosilicate identified as ZMQ-TB. The claimed ZMQ-TB crystalline titanoborosilicates are prepared by using titanium potassium oxalate, an alkali tetra-hydroborate and sodium silicate in the presence of an alkylammonium ion and/or a mineralization agent, such as sodium chloride under hydrothermal reaction conditions.
The product obtained has a specified X-ray diffraction pattern. The above X-ray diffraction pattern is applicable to all ZMQ-TB compositions. Such crystalline titanoborosilicates can generally be represented in terms of molar ratios of oxides by the formula: EQU 0.9.+-.0.2M.sub.2/n O:TiO.sub.2 :B.sub.2 O.sub.3 :ySiO.sub.2 :zH.sub.2 O
wherein M is at least one cation of valence n, y is a number between 8 and 500 and z is a number between 0 and 100. As taught herein, the TiO.sub.2 to B.sub.2 O.sub.3 ratio is equal to 1.
There is also provided a process for the conversion of alcohols such as methanol and ethanol into hydrocarbons using the ZMQ-TB titanoborosilicate.
Additional relevant prior art comprising U.S. Pat. No. 4,410,501, EP 0,094,024, Gr(German Pat.) 3,240,869 and Gr 3,240,870, relate to titanosilicates.
A further object of this invention is to provide a semiconductor loaded with metal for the cleavage of water.
In recent years considerable interest has been shown in the field of photocatalysts and solar energy conversion. In particular, a great deal of attention has focused on the use of semiconductors to cleave water photochemically, and of the many available semiconductors it is the n-type oxides such as titanium oxide, strontium titanate and cadmium sulfide which have been most widely used.
A photocatalyst may be constructed by depositing metals (Pt, Pd, Ru, Rh, Nb, Au, Cu, Ag) or some oxides (RuO.sub.2) onto a particle of a semiconductor.
These surface-modified photocatalysts, such as Pt/TiO.sub.2, have been used to photo-oxidise water, sulphite, cyanide, acetate, alcohols, hydrocarbons, carbohydrates, active carbon and biomass, and simultaneously reduce water.
The photocatalytic reactions can also be applied to organic synthesis of organic acids and amino acid synthesis.